For the high volume production machining of small components, the typical equipment used to accomplish the task of multi-station transfer machines, where at each work station a particular machining operation is performed. For example, typical stations will drill, ream, tap (etc.) one or several holes in each workpiece. The workpieces must be transferred into and out of each successive workstation.
For the transfer of the workpieces, the conventional methods include:
A. the use of pallets transferred between workstations, pallets being large fixtures onto which the workpieces are securely clamped before machining;
B. the use of a free transfer system without pellets, i.e. transferring only the workpieces into and out of a stationary work fixture.
Serious difficulties arise with the use of either the above-described conventional methods, when these are employed to transfer small and difficult to handle components. With the pallet method, a typical pallet can weigh up to 1200 pounds, thus dwarfing the weight of small components such as connecting rods. Where several stations are encountered, the method becomes unattractive from a cost point of view, considering the size and rigidity of the transfer mechanism, pallet clamping registries and the pallet return system.
The free transfer system is well known for the tendency of workpieces to fall out of the transfer mechanism and jam the equipment.